// SPDX-License-Identifier: GPL-2.0-only
/*
 * Functions to manage eBPF programs attached to cgroups
 *
 * Copyright (c) 2016 Daniel Mack
 */

#include <linux/kernel.h>
#include <linux/atomic.h>
#include <linux/cgroup.h>
#include <linux/filter.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/string.h>
#include <linux/bpf.h>
#include <linux/bpf-cgroup.h>
#include <linux/bpf_lsm.h>
#include <linux/bpf_verifier.h>
#include <net/sock.h>
#include <net/bpf_sk_storage.h>

#include "../cgroup/cgroup-internal.h"

DEFINE_STATIC_KEY_ARRAY_FALSE(cgroup_bpf_enabled_key, MAX_CGROUP_BPF_ATTACH_TYPE);
EXPORT_SYMBOL(cgroup_bpf_enabled_key);

/*
 * cgroup bpf destruction makes heavy use of work items and there can be a lot
 * of concurrent destructions.  Use a separate workqueue so that cgroup bpf
 * destruction work items don't end up filling up max_active of system_percpu_wq
 * which may lead to deadlock.
 */
static struct workqueue_struct *cgroup_bpf_destroy_wq;

static int __init cgroup_bpf_wq_init(void)
{
        cgroup_bpf_destroy_wq = alloc_workqueue("cgroup_bpf_destroy",
                                                WQ_PERCPU, 1);
        if (!cgroup_bpf_destroy_wq)
                panic("Failed to alloc workqueue for cgroup bpf destroy.\n");
        return 0;
}
core_initcall(cgroup_bpf_wq_init);

static int cgroup_bpf_lifetime_notify(struct notifier_block *nb,
                                      unsigned long action, void *data);

static struct notifier_block cgroup_bpf_lifetime_nb = {
        .notifier_call = cgroup_bpf_lifetime_notify,
};

void __init cgroup_bpf_lifetime_notifier_init(void)
{
        BUG_ON(blocking_notifier_chain_register(&cgroup_lifetime_notifier,
                                                &cgroup_bpf_lifetime_nb));
}

/* __always_inline is necessary to prevent indirect call through run_prog
 * function pointer.
 */
static __always_inline int
bpf_prog_run_array_cg(const struct cgroup_bpf *cgrp,
                      enum cgroup_bpf_attach_type atype,
                      const void *ctx, bpf_prog_run_fn run_prog,
                      int retval, u32 *ret_flags)
{
        const struct bpf_prog_array_item *item;
        const struct bpf_prog *prog;
        const struct bpf_prog_array *array;
        struct bpf_run_ctx *old_run_ctx;
        struct bpf_cg_run_ctx run_ctx;
        u32 func_ret;

        run_ctx.retval = retval;
        rcu_read_lock_dont_migrate();
        array = rcu_dereference(cgrp->effective[atype]);
        item = &array->items[0];
        old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
        while ((prog = READ_ONCE(item->prog))) {
                run_ctx.prog_item = item;
                func_ret = run_prog(prog, ctx);
                if (ret_flags) {
                        *(ret_flags) |= (func_ret >> 1);
                        func_ret &= 1;
                }
                if (!func_ret && !IS_ERR_VALUE((long)run_ctx.retval))
                        run_ctx.retval = -EPERM;
                item++;
        }
        bpf_reset_run_ctx(old_run_ctx);
        rcu_read_unlock_migrate();
        return run_ctx.retval;
}

unsigned int __cgroup_bpf_run_lsm_sock(const void *ctx,
                                       const struct bpf_insn *insn)
{
        const struct bpf_prog *shim_prog;
        struct sock *sk;
        struct cgroup *cgrp;
        int ret = 0;
        u64 *args;

        args = (u64 *)ctx;
        sk = (void *)(unsigned long)args[0];
        /*shim_prog = container_of(insn, struct bpf_prog, insnsi);*/
        shim_prog = (const struct bpf_prog *)((void *)insn - offsetof(struct bpf_prog, insnsi));

        cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        if (likely(cgrp))
                ret = bpf_prog_run_array_cg(&cgrp->bpf,
                                            shim_prog->aux->cgroup_atype,
                                            ctx, bpf_prog_run, 0, NULL);
        return ret;
}

unsigned int __cgroup_bpf_run_lsm_socket(const void *ctx,
                                         const struct bpf_insn *insn)
{
        const struct bpf_prog *shim_prog;
        struct socket *sock;
        struct cgroup *cgrp;
        int ret = 0;
        u64 *args;

        args = (u64 *)ctx;
        sock = (void *)(unsigned long)args[0];
        /*shim_prog = container_of(insn, struct bpf_prog, insnsi);*/
        shim_prog = (const struct bpf_prog *)((void *)insn - offsetof(struct bpf_prog, insnsi));

        cgrp = sock_cgroup_ptr(&sock->sk->sk_cgrp_data);
        if (likely(cgrp))
                ret = bpf_prog_run_array_cg(&cgrp->bpf,
                                            shim_prog->aux->cgroup_atype,
                                            ctx, bpf_prog_run, 0, NULL);
        return ret;
}

unsigned int __cgroup_bpf_run_lsm_current(const void *ctx,
                                          const struct bpf_insn *insn)
{
        const struct bpf_prog *shim_prog;
        struct cgroup *cgrp;
        int ret = 0;

        /*shim_prog = container_of(insn, struct bpf_prog, insnsi);*/
        shim_prog = (const struct bpf_prog *)((void *)insn - offsetof(struct bpf_prog, insnsi));

        /* We rely on trampoline's __bpf_prog_enter_lsm_cgroup to grab RCU read lock. */
        cgrp = task_dfl_cgroup(current);
        if (likely(cgrp))
                ret = bpf_prog_run_array_cg(&cgrp->bpf,
                                            shim_prog->aux->cgroup_atype,
                                            ctx, bpf_prog_run, 0, NULL);
        return ret;
}

#ifdef CONFIG_BPF_LSM
struct cgroup_lsm_atype {
        u32 attach_btf_id;
        int refcnt;
};

static struct cgroup_lsm_atype cgroup_lsm_atype[CGROUP_LSM_NUM];

static enum cgroup_bpf_attach_type
bpf_cgroup_atype_find(enum bpf_attach_type attach_type, u32 attach_btf_id)
{
        int i;

        lockdep_assert_held(&cgroup_mutex);

        if (attach_type != BPF_LSM_CGROUP)
                return to_cgroup_bpf_attach_type(attach_type);

        for (i = 0; i < ARRAY_SIZE(cgroup_lsm_atype); i++)
                if (cgroup_lsm_atype[i].attach_btf_id == attach_btf_id)
                        return CGROUP_LSM_START + i;

        for (i = 0; i < ARRAY_SIZE(cgroup_lsm_atype); i++)
                if (cgroup_lsm_atype[i].attach_btf_id == 0)
                        return CGROUP_LSM_START + i;

        return -E2BIG;

}

void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype)
{
        int i = cgroup_atype - CGROUP_LSM_START;

        lockdep_assert_held(&cgroup_mutex);

        WARN_ON_ONCE(cgroup_lsm_atype[i].attach_btf_id &&
                     cgroup_lsm_atype[i].attach_btf_id != attach_btf_id);

        cgroup_lsm_atype[i].attach_btf_id = attach_btf_id;
        cgroup_lsm_atype[i].refcnt++;
}

void bpf_cgroup_atype_put(int cgroup_atype)
{
        int i = cgroup_atype - CGROUP_LSM_START;

        cgroup_lock();
        if (--cgroup_lsm_atype[i].refcnt <= 0)
                cgroup_lsm_atype[i].attach_btf_id = 0;
        WARN_ON_ONCE(cgroup_lsm_atype[i].refcnt < 0);
        cgroup_unlock();
}
#else
static enum cgroup_bpf_attach_type
bpf_cgroup_atype_find(enum bpf_attach_type attach_type, u32 attach_btf_id)
{
        if (attach_type != BPF_LSM_CGROUP)
                return to_cgroup_bpf_attach_type(attach_type);
        return -EOPNOTSUPP;
}
#endif /* CONFIG_BPF_LSM */

static void cgroup_bpf_offline(struct cgroup *cgrp)
{
        cgroup_get(cgrp);
        percpu_ref_kill(&cgrp->bpf.refcnt);
}

static void bpf_cgroup_storages_free(struct bpf_cgroup_storage *storages[])
{
        enum bpf_cgroup_storage_type stype;

        for_each_cgroup_storage_type(stype)
                bpf_cgroup_storage_free(storages[stype]);
}

static int bpf_cgroup_storages_alloc(struct bpf_cgroup_storage *storages[],
                                     struct bpf_cgroup_storage *new_storages[],
                                     enum bpf_attach_type type,
                                     struct bpf_prog *prog,
                                     struct cgroup *cgrp)
{
        enum bpf_cgroup_storage_type stype;
        struct bpf_cgroup_storage_key key;
        struct bpf_map *map;

        key.cgroup_inode_id = cgroup_id(cgrp);
        key.attach_type = type;

        for_each_cgroup_storage_type(stype) {
                map = prog->aux->cgroup_storage[stype];
                if (!map)
                        continue;

                storages[stype] = cgroup_storage_lookup((void *)map, &key, false);
                if (storages[stype])
                        continue;

                storages[stype] = bpf_cgroup_storage_alloc(prog, stype);
                if (IS_ERR(storages[stype])) {
                        bpf_cgroup_storages_free(new_storages);
                        return -ENOMEM;
                }

                new_storages[stype] = storages[stype];
        }

        return 0;
}

static void bpf_cgroup_storages_assign(struct bpf_cgroup_storage *dst[],
                                       struct bpf_cgroup_storage *src[])
{
        enum bpf_cgroup_storage_type stype;

        for_each_cgroup_storage_type(stype)
                dst[stype] = src[stype];
}

static void bpf_cgroup_storages_link(struct bpf_cgroup_storage *storages[],
                                     struct cgroup *cgrp,
                                     enum bpf_attach_type attach_type)
{
        enum bpf_cgroup_storage_type stype;

        for_each_cgroup_storage_type(stype)
                bpf_cgroup_storage_link(storages[stype], cgrp, attach_type);
}

/* Called when bpf_cgroup_link is auto-detached from dying cgroup.
 * It drops cgroup and bpf_prog refcounts, and marks bpf_link as defunct. It
 * doesn't free link memory, which will eventually be done by bpf_link's
 * release() callback, when its last FD is closed.
 */
static void bpf_cgroup_link_auto_detach(struct bpf_cgroup_link *link)
{
        cgroup_put(link->cgroup);
        link->cgroup = NULL;
}

/**
 * cgroup_bpf_release() - put references of all bpf programs and
 *                        release all cgroup bpf data
 * @work: work structure embedded into the cgroup to modify
 */
static void cgroup_bpf_release(struct work_struct *work)
{
        struct cgroup *p, *cgrp = container_of(work, struct cgroup,
                                               bpf.release_work);
        struct bpf_prog_array *old_array;
        struct list_head *storages = &cgrp->bpf.storages;
        struct bpf_cgroup_storage *storage, *stmp;

        unsigned int atype;

        cgroup_lock();

        for (atype = 0; atype < ARRAY_SIZE(cgrp->bpf.progs); atype++) {
                struct hlist_head *progs = &cgrp->bpf.progs[atype];
                struct bpf_prog_list *pl;
                struct hlist_node *pltmp;

                hlist_for_each_entry_safe(pl, pltmp, progs, node) {
                        hlist_del(&pl->node);
                        if (pl->prog) {
                                if (pl->prog->expected_attach_type == BPF_LSM_CGROUP)
                                        bpf_trampoline_unlink_cgroup_shim(pl->prog);
                                bpf_prog_put(pl->prog);
                        }
                        if (pl->link) {
                                if (pl->link->link.prog->expected_attach_type == BPF_LSM_CGROUP)
                                        bpf_trampoline_unlink_cgroup_shim(pl->link->link.prog);
                                bpf_cgroup_link_auto_detach(pl->link);
                        }
                        kfree(pl);
                        static_branch_dec(&cgroup_bpf_enabled_key[atype]);
                }
                old_array = rcu_dereference_protected(
                                cgrp->bpf.effective[atype],
                                lockdep_is_held(&cgroup_mutex));
                bpf_prog_array_free(old_array);
        }

        list_for_each_entry_safe(storage, stmp, storages, list_cg) {
                bpf_cgroup_storage_unlink(storage);
                bpf_cgroup_storage_free(storage);
        }

        cgroup_unlock();

        for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
                cgroup_bpf_put(p);

        percpu_ref_exit(&cgrp->bpf.refcnt);
        cgroup_put(cgrp);
}

/**
 * cgroup_bpf_release_fn() - callback used to schedule releasing
 *                           of bpf cgroup data
 * @ref: percpu ref counter structure
 */
static void cgroup_bpf_release_fn(struct percpu_ref *ref)
{
        struct cgroup *cgrp = container_of(ref, struct cgroup, bpf.refcnt);

        INIT_WORK(&cgrp->bpf.release_work, cgroup_bpf_release);
        queue_work(cgroup_bpf_destroy_wq, &cgrp->bpf.release_work);
}

/* Get underlying bpf_prog of bpf_prog_list entry, regardless if it's through
 * link or direct prog.
 */
static struct bpf_prog *prog_list_prog(struct bpf_prog_list *pl)
{
        if (pl->prog)
                return pl->prog;
        if (pl->link)
                return pl->link->link.prog;
        return NULL;
}

/* count number of elements in the list.
 * it's slow but the list cannot be long
 */
static u32 prog_list_length(struct hlist_head *head, int *preorder_cnt)
{
        struct bpf_prog_list *pl;
        u32 cnt = 0;

        hlist_for_each_entry(pl, head, node) {
                if (!prog_list_prog(pl))
                        continue;
                if (preorder_cnt && (pl->flags & BPF_F_PREORDER))
                        (*preorder_cnt)++;
                cnt++;
        }
        return cnt;
}

/* if parent has non-overridable prog attached,
 * disallow attaching new programs to the descendent cgroup.
 * if parent has overridable or multi-prog, allow attaching
 */
static bool hierarchy_allows_attach(struct cgroup *cgrp,
                                    enum cgroup_bpf_attach_type atype)
{
        struct cgroup *p;

        p = cgroup_parent(cgrp);
        if (!p)
                return true;
        do {
                u32 flags = p->bpf.flags[atype];
                u32 cnt;

                if (flags & BPF_F_ALLOW_MULTI)
                        return true;
                cnt = prog_list_length(&p->bpf.progs[atype], NULL);
                WARN_ON_ONCE(cnt > 1);
                if (cnt == 1)
                        return !!(flags & BPF_F_ALLOW_OVERRIDE);
                p = cgroup_parent(p);
        } while (p);
        return true;
}

/* compute a chain of effective programs for a given cgroup:
 * start from the list of programs in this cgroup and add
 * all parent programs.
 * Note that parent's F_ALLOW_OVERRIDE-type program is yielding
 * to programs in this cgroup
 */
static int compute_effective_progs(struct cgroup *cgrp,
                                   enum cgroup_bpf_attach_type atype,
                                   struct bpf_prog_array **array)
{
        struct bpf_prog_array_item *item;
        struct bpf_prog_array *progs;
        struct bpf_prog_list *pl;
        struct cgroup *p = cgrp;
        int i, j, cnt = 0, preorder_cnt = 0, fstart, bstart, init_bstart;

        /* count number of effective programs by walking parents */
        do {
                if (cnt == 0 || (p->bpf.flags[atype] & BPF_F_ALLOW_MULTI))
                        cnt += prog_list_length(&p->bpf.progs[atype], &preorder_cnt);
                p = cgroup_parent(p);
        } while (p);

        progs = bpf_prog_array_alloc(cnt, GFP_KERNEL);
        if (!progs)
                return -ENOMEM;

        /* populate the array with effective progs */
        cnt = 0;
        p = cgrp;
        fstart = preorder_cnt;
        bstart = preorder_cnt - 1;
        do {
                if (cnt > 0 && !(p->bpf.flags[atype] & BPF_F_ALLOW_MULTI))
                        continue;

                init_bstart = bstart;
                hlist_for_each_entry(pl, &p->bpf.progs[atype], node) {
                        if (!prog_list_prog(pl))
                                continue;

                        if (pl->flags & BPF_F_PREORDER) {
                                item = &progs->items[bstart];
                                bstart--;
                        } else {
                                item = &progs->items[fstart];
                                fstart++;
                        }
                        item->prog = prog_list_prog(pl);
                        bpf_cgroup_storages_assign(item->cgroup_storage,
                                                   pl->storage);
                        cnt++;
                }

                /* reverse pre-ordering progs at this cgroup level */
                for (i = bstart + 1, j = init_bstart; i < j; i++, j--)
                        swap(progs->items[i], progs->items[j]);

        } while ((p = cgroup_parent(p)));

        *array = progs;
        return 0;
}

static void activate_effective_progs(struct cgroup *cgrp,
                                     enum cgroup_bpf_attach_type atype,
                                     struct bpf_prog_array *old_array)
{
        old_array = rcu_replace_pointer(cgrp->bpf.effective[atype], old_array,
                                        lockdep_is_held(&cgroup_mutex));
        /* free prog array after grace period, since __cgroup_bpf_run_*()
         * might be still walking the array
         */
        bpf_prog_array_free(old_array);
}

/**
 * cgroup_bpf_inherit() - inherit effective programs from parent
 * @cgrp: the cgroup to modify
 */
static int cgroup_bpf_inherit(struct cgroup *cgrp)
{
/* has to use marco instead of const int, since compiler thinks
 * that array below is variable length
 */
#define NR ARRAY_SIZE(cgrp->bpf.effective)
        struct bpf_prog_array *arrays[NR] = {};
        struct cgroup *p;
        int ret, i;

        ret = percpu_ref_init(&cgrp->bpf.refcnt, cgroup_bpf_release_fn, 0,
                              GFP_KERNEL);
        if (ret)
                return ret;

        for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
                cgroup_bpf_get(p);

        for (i = 0; i < NR; i++)
                INIT_HLIST_HEAD(&cgrp->bpf.progs[i]);

        INIT_LIST_HEAD(&cgrp->bpf.storages);

        for (i = 0; i < NR; i++)
                if (compute_effective_progs(cgrp, i, &arrays[i]))
                        goto cleanup;

        for (i = 0; i < NR; i++)
                activate_effective_progs(cgrp, i, arrays[i]);

        return 0;
cleanup:
        for (i = 0; i < NR; i++)
                bpf_prog_array_free(arrays[i]);

        for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
                cgroup_bpf_put(p);

        percpu_ref_exit(&cgrp->bpf.refcnt);

        return -ENOMEM;
}

static int cgroup_bpf_lifetime_notify(struct notifier_block *nb,
                                      unsigned long action, void *data)
{
        struct cgroup *cgrp = data;
        int ret = 0;

        if (cgrp->root != &cgrp_dfl_root)
                return NOTIFY_OK;

        switch (action) {
        case CGROUP_LIFETIME_ONLINE:
                ret = cgroup_bpf_inherit(cgrp);
                break;
        case CGROUP_LIFETIME_OFFLINE:
                cgroup_bpf_offline(cgrp);
                break;
        }

        return notifier_from_errno(ret);
}

static int update_effective_progs(struct cgroup *cgrp,
                                  enum cgroup_bpf_attach_type atype)
{
        struct cgroup_subsys_state *css;
        int err;

        /* allocate and recompute effective prog arrays */
        css_for_each_descendant_pre(css, &cgrp->self) {
                struct cgroup *desc = container_of(css, struct cgroup, self);

                if (percpu_ref_is_zero(&desc->bpf.refcnt))
                        continue;

                err = compute_effective_progs(desc, atype, &desc->bpf.inactive);
                if (err)
                        goto cleanup;
        }

        /* all allocations were successful. Activate all prog arrays */
        css_for_each_descendant_pre(css, &cgrp->self) {
                struct cgroup *desc = container_of(css, struct cgroup, self);

                if (percpu_ref_is_zero(&desc->bpf.refcnt)) {
                        if (unlikely(desc->bpf.inactive)) {
                                bpf_prog_array_free(desc->bpf.inactive);
                                desc->bpf.inactive = NULL;
                        }
                        continue;
                }

                activate_effective_progs(desc, atype, desc->bpf.inactive);
                desc->bpf.inactive = NULL;
        }

        return 0;

cleanup:
        /* oom while computing effective. Free all computed effective arrays
         * since they were not activated
         */
        css_for_each_descendant_pre(css, &cgrp->self) {
                struct cgroup *desc = container_of(css, struct cgroup, self);

                bpf_prog_array_free(desc->bpf.inactive);
                desc->bpf.inactive = NULL;
        }

        return err;
}

#define BPF_CGROUP_MAX_PROGS 64

static struct bpf_prog_list *find_attach_entry(struct hlist_head *progs,
                                               struct bpf_prog *prog,
                                               struct bpf_cgroup_link *link,
                                               struct bpf_prog *replace_prog,
                                               bool allow_multi)
{
        struct bpf_prog_list *pl;

        /* single-attach case */
        if (!allow_multi) {
                if (hlist_empty(progs))
                        return NULL;
                return hlist_entry(progs->first, typeof(*pl), node);
        }

        hlist_for_each_entry(pl, progs, node) {
                if (prog && pl->prog == prog && prog != replace_prog)
                        /* disallow attaching the same prog twice */
                        return ERR_PTR(-EINVAL);
                if (link && pl->link == link)
                        /* disallow attaching the same link twice */
                        return ERR_PTR(-EINVAL);
        }

        /* direct prog multi-attach w/ replacement case */
        if (replace_prog) {
                hlist_for_each_entry(pl, progs, node) {
                        if (pl->prog == replace_prog)
                                /* a match found */
                                return pl;
                }
                /* prog to replace not found for cgroup */
                return ERR_PTR(-ENOENT);
        }

        return NULL;
}

static struct bpf_link *bpf_get_anchor_link(u32 flags, u32 id_or_fd)
{
        struct bpf_link *link = ERR_PTR(-EINVAL);

        if (flags & BPF_F_ID)
                link = bpf_link_by_id(id_or_fd);
        else if (id_or_fd)
                link = bpf_link_get_from_fd(id_or_fd);
        return link;
}

static struct bpf_prog *bpf_get_anchor_prog(u32 flags, u32 id_or_fd)
{
        struct bpf_prog *prog = ERR_PTR(-EINVAL);

        if (flags & BPF_F_ID)
                prog = bpf_prog_by_id(id_or_fd);
        else if (id_or_fd)
                prog = bpf_prog_get(id_or_fd);
        return prog;
}

static struct bpf_prog_list *get_prog_list(struct hlist_head *progs, struct bpf_prog *prog,
                                           struct bpf_cgroup_link *link, u32 flags, u32 id_or_fd)
{
        bool is_link = flags & BPF_F_LINK, is_id = flags & BPF_F_ID;
        struct bpf_prog_list *pltmp, *pl = ERR_PTR(-EINVAL);
        bool preorder = flags & BPF_F_PREORDER;
        struct bpf_link *anchor_link = NULL;
        struct bpf_prog *anchor_prog = NULL;
        bool is_before, is_after;

        is_before = flags & BPF_F_BEFORE;
        is_after = flags & BPF_F_AFTER;
        if (is_link || is_id || id_or_fd) {
                /* flags must have either BPF_F_BEFORE or BPF_F_AFTER */
                if (is_before == is_after)
                        return ERR_PTR(-EINVAL);
                if ((is_link && !link) || (!is_link && !prog))
                        return ERR_PTR(-EINVAL);
        } else if (!hlist_empty(progs)) {
                /* flags cannot have both BPF_F_BEFORE and BPF_F_AFTER */
                if (is_before && is_after)
                        return ERR_PTR(-EINVAL);
        }

        if (is_link) {
                anchor_link = bpf_get_anchor_link(flags, id_or_fd);
                if (IS_ERR(anchor_link))
                        return ERR_CAST(anchor_link);
        } else if (is_id || id_or_fd) {
                anchor_prog = bpf_get_anchor_prog(flags, id_or_fd);
                if (IS_ERR(anchor_prog))
                        return ERR_CAST(anchor_prog);
        }

        if (!anchor_prog && !anchor_link) {
                /* if there is no anchor_prog/anchor_link, then BPF_F_PREORDER
                 * doesn't matter since either prepend or append to a combined
                 * list of progs will end up with correct result.
                 */
                hlist_for_each_entry(pltmp, progs, node) {
                        if (is_before)
                                return pltmp;
                        if (pltmp->node.next)
                                continue;
                        return pltmp;
                }
                return NULL;
        }

        hlist_for_each_entry(pltmp, progs, node) {
                if ((anchor_prog && anchor_prog == pltmp->prog) ||
                    (anchor_link && anchor_link == &pltmp->link->link)) {
                        if (!!(pltmp->flags & BPF_F_PREORDER) != preorder)
                                goto out;
                        pl = pltmp;
                        goto out;
                }
        }

        pl = ERR_PTR(-ENOENT);
out:
        if (anchor_link)
                bpf_link_put(anchor_link);
        else
                bpf_prog_put(anchor_prog);
        return pl;
}

static int insert_pl_to_hlist(struct bpf_prog_list *pl, struct hlist_head *progs,
                              struct bpf_prog *prog, struct bpf_cgroup_link *link,
                              u32 flags, u32 id_or_fd)
{
        struct bpf_prog_list *pltmp;

        pltmp = get_prog_list(progs, prog, link, flags, id_or_fd);
        if (IS_ERR(pltmp))
                return PTR_ERR(pltmp);

        if (!pltmp)
                hlist_add_head(&pl->node, progs);
        else if (flags & BPF_F_BEFORE)
                hlist_add_before(&pl->node, &pltmp->node);
        else
                hlist_add_behind(&pl->node, &pltmp->node);

        return 0;
}

/**
 * __cgroup_bpf_attach() - Attach the program or the link to a cgroup, and
 *                         propagate the change to descendants
 * @cgrp: The cgroup which descendants to traverse
 * @prog: A program to attach
 * @link: A link to attach
 * @replace_prog: Previously attached program to replace if BPF_F_REPLACE is set
 * @type: Type of attach operation
 * @flags: Option flags
 * @id_or_fd: Relative prog id or fd
 * @revision: bpf_prog_list revision
 *
 * Exactly one of @prog or @link can be non-null.
 * Must be called with cgroup_mutex held.
 */
static int __cgroup_bpf_attach(struct cgroup *cgrp,
                               struct bpf_prog *prog, struct bpf_prog *replace_prog,
                               struct bpf_cgroup_link *link,
                               enum bpf_attach_type type, u32 flags, u32 id_or_fd,
                               u64 revision)
{
        u32 saved_flags = (flags & (BPF_F_ALLOW_OVERRIDE | BPF_F_ALLOW_MULTI));
        struct bpf_prog *old_prog = NULL;
        struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
        struct bpf_cgroup_storage *new_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
        struct bpf_prog *new_prog = prog ? : link->link.prog;
        enum cgroup_bpf_attach_type atype;
        struct bpf_prog_list *pl;
        struct hlist_head *progs;
        int err;

        if (((flags & BPF_F_ALLOW_OVERRIDE) && (flags & BPF_F_ALLOW_MULTI)) ||
            ((flags & BPF_F_REPLACE) && !(flags & BPF_F_ALLOW_MULTI)))
                /* invalid combination */
                return -EINVAL;
        if ((flags & BPF_F_REPLACE) && (flags & (BPF_F_BEFORE | BPF_F_AFTER)))
                /* only either replace or insertion with before/after */
                return -EINVAL;
        if (link && (prog || replace_prog))
                /* only either link or prog/replace_prog can be specified */
                return -EINVAL;
        if (!!replace_prog != !!(flags & BPF_F_REPLACE))
                /* replace_prog implies BPF_F_REPLACE, and vice versa */
                return -EINVAL;

        atype = bpf_cgroup_atype_find(type, new_prog->aux->attach_btf_id);
        if (atype < 0)
                return -EINVAL;
        if (revision && revision != cgrp->bpf.revisions[atype])
                return -ESTALE;

        progs = &cgrp->bpf.progs[atype];

        if (!hierarchy_allows_attach(cgrp, atype))
                return -EPERM;

        if (!hlist_empty(progs) && cgrp->bpf.flags[atype] != saved_flags)
                /* Disallow attaching non-overridable on top
                 * of existing overridable in this cgroup.
                 * Disallow attaching multi-prog if overridable or none
                 */
                return -EPERM;

        if (prog_list_length(progs, NULL) >= BPF_CGROUP_MAX_PROGS)
                return -E2BIG;

        pl = find_attach_entry(progs, prog, link, replace_prog,
                               flags & BPF_F_ALLOW_MULTI);
        if (IS_ERR(pl))
                return PTR_ERR(pl);

        if (bpf_cgroup_storages_alloc(storage, new_storage, type,
                                      prog ? : link->link.prog, cgrp))
                return -ENOMEM;

        if (pl) {
                old_prog = pl->prog;
        } else {
                pl = kmalloc_obj(*pl);
                if (!pl) {
                        bpf_cgroup_storages_free(new_storage);
                        return -ENOMEM;
                }

                err = insert_pl_to_hlist(pl, progs, prog, link, flags, id_or_fd);
                if (err) {
                        kfree(pl);
                        bpf_cgroup_storages_free(new_storage);
                        return err;
                }
        }

        pl->prog = prog;
        pl->link = link;
        pl->flags = flags;
        bpf_cgroup_storages_assign(pl->storage, storage);
        cgrp->bpf.flags[atype] = saved_flags;

        if (type == BPF_LSM_CGROUP) {
                err = bpf_trampoline_link_cgroup_shim(new_prog, atype, type);
                if (err)
                        goto cleanup;
        }

        err = update_effective_progs(cgrp, atype);
        if (err)
                goto cleanup_trampoline;

        cgrp->bpf.revisions[atype] += 1;
        if (old_prog) {
                if (type == BPF_LSM_CGROUP)
                        bpf_trampoline_unlink_cgroup_shim(old_prog);
                bpf_prog_put(old_prog);
        } else {
                static_branch_inc(&cgroup_bpf_enabled_key[atype]);
        }
        bpf_cgroup_storages_link(new_storage, cgrp, type);
        return 0;

cleanup_trampoline:
        if (type == BPF_LSM_CGROUP)
                bpf_trampoline_unlink_cgroup_shim(new_prog);

cleanup:
        if (old_prog) {
                pl->prog = old_prog;
                pl->link = NULL;
        }
        bpf_cgroup_storages_free(new_storage);
        if (!old_prog) {
                hlist_del(&pl->node);
                kfree(pl);
        }
        return err;
}

static int cgroup_bpf_attach(struct cgroup *cgrp,
                             struct bpf_prog *prog, struct bpf_prog *replace_prog,
                             struct bpf_cgroup_link *link,
                             enum bpf_attach_type type,
                             u32 flags, u32 id_or_fd, u64 revision)
{
        int ret;

        cgroup_lock();
        ret = __cgroup_bpf_attach(cgrp, prog, replace_prog, link, type, flags,
                                  id_or_fd, revision);
        cgroup_unlock();
        return ret;
}

/* Swap updated BPF program for given link in effective program arrays across
 * all descendant cgroups. This function is guaranteed to succeed.
 */
static void replace_effective_prog(struct cgroup *cgrp,
                                   enum cgroup_bpf_attach_type atype,
                                   struct bpf_cgroup_link *link)
{
        struct bpf_prog_array_item *item;
        struct cgroup_subsys_state *css;
        struct bpf_prog_array *progs;
        struct bpf_prog_list *pl;
        struct hlist_head *head;
        struct cgroup *cg;
        int pos;

        css_for_each_descendant_pre(css, &cgrp->self) {
                struct cgroup *desc = container_of(css, struct cgroup, self);

                if (percpu_ref_is_zero(&desc->bpf.refcnt))
                        continue;

                /* find position of link in effective progs array */
                for (pos = 0, cg = desc; cg; cg = cgroup_parent(cg)) {
                        if (pos && !(cg->bpf.flags[atype] & BPF_F_ALLOW_MULTI))
                                continue;

                        head = &cg->bpf.progs[atype];
                        hlist_for_each_entry(pl, head, node) {
                                if (!prog_list_prog(pl))
                                        continue;
                                if (pl->link == link)
                                        goto found;
                                pos++;
                        }
                }
found:
                BUG_ON(!cg);
                progs = rcu_dereference_protected(
                                desc->bpf.effective[atype],
                                lockdep_is_held(&cgroup_mutex));
                item = &progs->items[pos];
                WRITE_ONCE(item->prog, link->link.prog);
        }
}

/**
 * __cgroup_bpf_replace() - Replace link's program and propagate the change
 *                          to descendants
 * @cgrp: The cgroup which descendants to traverse
 * @link: A link for which to replace BPF program
 * @new_prog: &struct bpf_prog for the target BPF program with its refcnt
 *            incremented
 *
 * Must be called with cgroup_mutex held.
 */
static int __cgroup_bpf_replace(struct cgroup *cgrp,
                                struct bpf_cgroup_link *link,
                                struct bpf_prog *new_prog)
{
        enum cgroup_bpf_attach_type atype;
        struct bpf_prog *old_prog;
        struct bpf_prog_list *pl;
        struct hlist_head *progs;
        bool found = false;

        atype = bpf_cgroup_atype_find(link->link.attach_type, new_prog->aux->attach_btf_id);
        if (atype < 0)
                return -EINVAL;

        progs = &cgrp->bpf.progs[atype];

        if (link->link.prog->type != new_prog->type)
                return -EINVAL;

        hlist_for_each_entry(pl, progs, node) {
                if (pl->link == link) {
                        found = true;
                        break;
                }
        }
        if (!found)
                return -ENOENT;

        cgrp->bpf.revisions[atype] += 1;
        old_prog = xchg(&link->link.prog, new_prog);
        replace_effective_prog(cgrp, atype, link);
        bpf_prog_put(old_prog);
        return 0;
}

static int cgroup_bpf_replace(struct bpf_link *link, struct bpf_prog *new_prog,
                              struct bpf_prog *old_prog)
{
        struct bpf_cgroup_link *cg_link;
        int ret;

        cg_link = container_of(link, struct bpf_cgroup_link, link);

        cgroup_lock();
        /* link might have been auto-released by dying cgroup, so fail */
        if (!cg_link->cgroup) {
                ret = -ENOLINK;
                goto out_unlock;
        }
        if (old_prog && link->prog != old_prog) {
                ret = -EPERM;
                goto out_unlock;
        }
        ret = __cgroup_bpf_replace(cg_link->cgroup, cg_link, new_prog);
out_unlock:
        cgroup_unlock();
        return ret;
}

static struct bpf_prog_list *find_detach_entry(struct hlist_head *progs,
                                               struct bpf_prog *prog,
                                               struct bpf_cgroup_link *link,
                                               bool allow_multi)
{
        struct bpf_prog_list *pl;

        if (!allow_multi) {
                if (hlist_empty(progs))
                        /* report error when trying to detach and nothing is attached */
                        return ERR_PTR(-ENOENT);

                /* to maintain backward compatibility NONE and OVERRIDE cgroups
                 * allow detaching with invalid FD (prog==NULL) in legacy mode
                 */
                return hlist_entry(progs->first, typeof(*pl), node);
        }

        if (!prog && !link)
                /* to detach MULTI prog the user has to specify valid FD
                 * of the program or link to be detached
                 */
                return ERR_PTR(-EINVAL);

        /* find the prog or link and detach it */
        hlist_for_each_entry(pl, progs, node) {
                if (pl->prog == prog && pl->link == link)
                        return pl;
        }
        return ERR_PTR(-ENOENT);
}

/**
 * purge_effective_progs() - After compute_effective_progs fails to alloc new
 *                           cgrp->bpf.inactive table we can recover by
 *                           recomputing the array in place.
 *
 * @cgrp: The cgroup which descendants to travers
 * @prog: A program to detach or NULL
 * @link: A link to detach or NULL
 * @atype: Type of detach operation
 */
static void purge_effective_progs(struct cgroup *cgrp, struct bpf_prog *prog,
                                  struct bpf_cgroup_link *link,
                                  enum cgroup_bpf_attach_type atype)
{
        struct cgroup_subsys_state *css;
        struct bpf_prog_array *progs;
        struct bpf_prog_list *pl;
        struct hlist_head *head;
        struct cgroup *cg;
        int pos;

        /* recompute effective prog array in place */
        css_for_each_descendant_pre(css, &cgrp->self) {
                struct cgroup *desc = container_of(css, struct cgroup, self);

                if (percpu_ref_is_zero(&desc->bpf.refcnt))
                        continue;

                /* find position of link or prog in effective progs array */
                for (pos = 0, cg = desc; cg; cg = cgroup_parent(cg)) {
                        if (pos && !(cg->bpf.flags[atype] & BPF_F_ALLOW_MULTI))
                                continue;

                        head = &cg->bpf.progs[atype];
                        hlist_for_each_entry(pl, head, node) {
                                if (!prog_list_prog(pl))
                                        continue;
                                if (pl->prog == prog && pl->link == link)
                                        goto found;
                                pos++;
                        }
                }

                /* no link or prog match, skip the cgroup of this layer */
                continue;
found:
                progs = rcu_dereference_protected(
                                desc->bpf.effective[atype],
                                lockdep_is_held(&cgroup_mutex));

                /* Remove the program from the array */
                WARN_ONCE(bpf_prog_array_delete_safe_at(progs, pos),
                          "Failed to purge a prog from array at index %d", pos);
        }
}

/**
 * __cgroup_bpf_detach() - Detach the program or link from a cgroup, and
 *                         propagate the change to descendants
 * @cgrp: The cgroup which descendants to traverse
 * @prog: A program to detach or NULL
 * @link: A link to detach or NULL
 * @type: Type of detach operation
 * @revision: bpf_prog_list revision
 *
 * At most one of @prog or @link can be non-NULL.
 * Must be called with cgroup_mutex held.
 */
static int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
                               struct bpf_cgroup_link *link, enum bpf_attach_type type,
                               u64 revision)
{
        enum cgroup_bpf_attach_type atype;
        struct bpf_prog *old_prog;
        struct bpf_prog_list *pl;
        struct hlist_head *progs;
        u32 attach_btf_id = 0;
        u32 flags;

        if (prog)
                attach_btf_id = prog->aux->attach_btf_id;
        if (link)
                attach_btf_id = link->link.prog->aux->attach_btf_id;

        atype = bpf_cgroup_atype_find(type, attach_btf_id);
        if (atype < 0)
                return -EINVAL;

        if (revision && revision != cgrp->bpf.revisions[atype])
                return -ESTALE;

        progs = &cgrp->bpf.progs[atype];
        flags = cgrp->bpf.flags[atype];

        if (prog && link)
                /* only one of prog or link can be specified */
                return -EINVAL;

        pl = find_detach_entry(progs, prog, link, flags & BPF_F_ALLOW_MULTI);
        if (IS_ERR(pl))
                return PTR_ERR(pl);

        /* mark it deleted, so it's ignored while recomputing effective */
        old_prog = pl->prog;
        pl->prog = NULL;
        pl->link = NULL;

        if (update_effective_progs(cgrp, atype)) {
                /* if update effective array failed replace the prog with a dummy prog*/
                pl->prog = old_prog;
                pl->link = link;
                purge_effective_progs(cgrp, old_prog, link, atype);
        }

        /* now can actually delete it from this cgroup list */
        hlist_del(&pl->node);
        cgrp->bpf.revisions[atype] += 1;

        kfree(pl);
        if (hlist_empty(progs))
                /* last program was detached, reset flags to zero */
                cgrp->bpf.flags[atype] = 0;
        if (old_prog) {
                if (type == BPF_LSM_CGROUP)
                        bpf_trampoline_unlink_cgroup_shim(old_prog);
                bpf_prog_put(old_prog);
        }
        static_branch_dec(&cgroup_bpf_enabled_key[atype]);
        return 0;
}

static int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
                             enum bpf_attach_type type, u64 revision)
{
        int ret;

        cgroup_lock();
        ret = __cgroup_bpf_detach(cgrp, prog, NULL, type, revision);
        cgroup_unlock();
        return ret;
}

/* Must be called with cgroup_mutex held to avoid races. */
static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
                              union bpf_attr __user *uattr)
{
        __u32 __user *prog_attach_flags = u64_to_user_ptr(attr->query.prog_attach_flags);
        bool effective_query = attr->query.query_flags & BPF_F_QUERY_EFFECTIVE;
        __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
        enum bpf_attach_type type = attr->query.attach_type;
        enum cgroup_bpf_attach_type from_atype, to_atype;
        enum cgroup_bpf_attach_type atype;
        struct bpf_prog_array *effective;
        int cnt, ret = 0, i;
        int total_cnt = 0;
        u64 revision = 0;
        u32 flags;

        if (effective_query && prog_attach_flags)
                return -EINVAL;

        if (type == BPF_LSM_CGROUP) {
                if (!effective_query && attr->query.prog_cnt &&
                    prog_ids && !prog_attach_flags)
                        return -EINVAL;

                from_atype = CGROUP_LSM_START;
                to_atype = CGROUP_LSM_END;
                flags = 0;
        } else {
                from_atype = to_cgroup_bpf_attach_type(type);
                if (from_atype < 0)
                        return -EINVAL;
                to_atype = from_atype;
                flags = cgrp->bpf.flags[from_atype];
        }

        for (atype = from_atype; atype <= to_atype; atype++) {
                if (effective_query) {
                        effective = rcu_dereference_protected(cgrp->bpf.effective[atype],
                                                              lockdep_is_held(&cgroup_mutex));
                        total_cnt += bpf_prog_array_length(effective);
                } else {
                        total_cnt += prog_list_length(&cgrp->bpf.progs[atype], NULL);
                }
        }

        /* always output uattr->query.attach_flags as 0 during effective query */
        flags = effective_query ? 0 : flags;
        if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
                return -EFAULT;
        if (copy_to_user(&uattr->query.prog_cnt, &total_cnt, sizeof(total_cnt)))
                return -EFAULT;
        if (!effective_query && from_atype == to_atype)
                revision = cgrp->bpf.revisions[from_atype];
        if (copy_to_user(&uattr->query.revision, &revision, sizeof(revision)))
                return -EFAULT;
        if (attr->query.prog_cnt == 0 || !prog_ids || !total_cnt)
                /* return early if user requested only program count + flags */
                return 0;

        if (attr->query.prog_cnt < total_cnt) {
                total_cnt = attr->query.prog_cnt;
                ret = -ENOSPC;
        }

        for (atype = from_atype; atype <= to_atype && total_cnt; atype++) {
                if (effective_query) {
                        effective = rcu_dereference_protected(cgrp->bpf.effective[atype],
                                                              lockdep_is_held(&cgroup_mutex));
                        cnt = min_t(int, bpf_prog_array_length(effective), total_cnt);
                        ret = bpf_prog_array_copy_to_user(effective, prog_ids, cnt);
                } else {
                        struct hlist_head *progs;
                        struct bpf_prog_list *pl;
                        struct bpf_prog *prog;
                        u32 id;

                        progs = &cgrp->bpf.progs[atype];
                        cnt = min_t(int, prog_list_length(progs, NULL), total_cnt);
                        i = 0;
                        hlist_for_each_entry(pl, progs, node) {
                                prog = prog_list_prog(pl);
                                id = prog->aux->id;
                                if (copy_to_user(prog_ids + i, &id, sizeof(id)))
                                        return -EFAULT;
                                if (++i == cnt)
                                        break;
                        }

                        if (prog_attach_flags) {
                                flags = cgrp->bpf.flags[atype];

                                for (i = 0; i < cnt; i++)
                                        if (copy_to_user(prog_attach_flags + i,
                                                         &flags, sizeof(flags)))
                                                return -EFAULT;
                                prog_attach_flags += cnt;
                        }
                }

                prog_ids += cnt;
                total_cnt -= cnt;
        }
        return ret;
}

static int cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
                            union bpf_attr __user *uattr)
{
        int ret;

        cgroup_lock();
        ret = __cgroup_bpf_query(cgrp, attr, uattr);
        cgroup_unlock();
        return ret;
}

int cgroup_bpf_prog_attach(const union bpf_attr *attr,
                           enum bpf_prog_type ptype, struct bpf_prog *prog)
{
        struct bpf_prog *replace_prog = NULL;
        struct cgroup *cgrp;
        int ret;

        cgrp = cgroup_get_from_fd(attr->target_fd);
        if (IS_ERR(cgrp))
                return PTR_ERR(cgrp);

        if ((attr->attach_flags & BPF_F_ALLOW_MULTI) &&
            (attr->attach_flags & BPF_F_REPLACE)) {
                replace_prog = bpf_prog_get_type(attr->replace_bpf_fd, ptype);
                if (IS_ERR(replace_prog)) {
                        cgroup_put(cgrp);
                        return PTR_ERR(replace_prog);
                }
        }

        ret = cgroup_bpf_attach(cgrp, prog, replace_prog, NULL,
                                attr->attach_type, attr->attach_flags,
                                attr->relative_fd, attr->expected_revision);

        if (replace_prog)
                bpf_prog_put(replace_prog);
        cgroup_put(cgrp);
        return ret;
}

int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
{
        struct bpf_prog *prog;
        struct cgroup *cgrp;
        int ret;

        cgrp = cgroup_get_from_fd(attr->target_fd);
        if (IS_ERR(cgrp))
                return PTR_ERR(cgrp);

        prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
        if (IS_ERR(prog))
                prog = NULL;

        ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type, attr->expected_revision);
        if (prog)
                bpf_prog_put(prog);

        cgroup_put(cgrp);
        return ret;
}

static void bpf_cgroup_link_release(struct bpf_link *link)
{
        struct bpf_cgroup_link *cg_link =
                container_of(link, struct bpf_cgroup_link, link);
        struct cgroup *cg;

        /* link might have been auto-detached by dying cgroup already,
         * in that case our work is done here
         */
        if (!cg_link->cgroup)
                return;

        cgroup_lock();

        /* re-check cgroup under lock again */
        if (!cg_link->cgroup) {
                cgroup_unlock();
                return;
        }

        WARN_ON(__cgroup_bpf_detach(cg_link->cgroup, NULL, cg_link,
                                    link->attach_type, 0));
        if (link->attach_type == BPF_LSM_CGROUP)
                bpf_trampoline_unlink_cgroup_shim(cg_link->link.prog);

        cg = cg_link->cgroup;
        cg_link->cgroup = NULL;

        cgroup_unlock();

        cgroup_put(cg);
}

static void bpf_cgroup_link_dealloc(struct bpf_link *link)
{
        struct bpf_cgroup_link *cg_link =
                container_of(link, struct bpf_cgroup_link, link);

        kfree(cg_link);
}

static int bpf_cgroup_link_detach(struct bpf_link *link)
{
        bpf_cgroup_link_release(link);

        return 0;
}

static void bpf_cgroup_link_show_fdinfo(const struct bpf_link *link,
                                        struct seq_file *seq)
{
        struct bpf_cgroup_link *cg_link =
                container_of(link, struct bpf_cgroup_link, link);
        u64 cg_id = 0;

        cgroup_lock();
        if (cg_link->cgroup)
                cg_id = cgroup_id(cg_link->cgroup);
        cgroup_unlock();

        seq_printf(seq,
                   "cgroup_id:\t%llu\n"
                   "attach_type:\t%d\n",
                   cg_id,
                   link->attach_type);
}

static int bpf_cgroup_link_fill_link_info(const struct bpf_link *link,
                                          struct bpf_link_info *info)
{
        struct bpf_cgroup_link *cg_link =
                container_of(link, struct bpf_cgroup_link, link);
        u64 cg_id = 0;

        cgroup_lock();
        if (cg_link->cgroup)
                cg_id = cgroup_id(cg_link->cgroup);
        cgroup_unlock();

        info->cgroup.cgroup_id = cg_id;
        info->cgroup.attach_type = link->attach_type;
        return 0;
}

static const struct bpf_link_ops bpf_cgroup_link_lops = {
        .release = bpf_cgroup_link_release,
        .dealloc = bpf_cgroup_link_dealloc,
        .detach = bpf_cgroup_link_detach,
        .update_prog = cgroup_bpf_replace,
        .show_fdinfo = bpf_cgroup_link_show_fdinfo,
        .fill_link_info = bpf_cgroup_link_fill_link_info,
};

#define BPF_F_LINK_ATTACH_MASK  \
        (BPF_F_ID |             \
         BPF_F_BEFORE |         \
         BPF_F_AFTER |          \
         BPF_F_PREORDER |       \
         BPF_F_LINK)

int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
        struct bpf_link_primer link_primer;
        struct bpf_cgroup_link *link;
        struct cgroup *cgrp;
        int err;

        if (attr->link_create.flags & (~BPF_F_LINK_ATTACH_MASK))
                return -EINVAL;

        cgrp = cgroup_get_from_fd(attr->link_create.target_fd);
        if (IS_ERR(cgrp))
                return PTR_ERR(cgrp);

        link = kzalloc_obj(*link, GFP_USER);
        if (!link) {
                err = -ENOMEM;
                goto out_put_cgroup;
        }
        bpf_link_init(&link->link, BPF_LINK_TYPE_CGROUP, &bpf_cgroup_link_lops,
                      prog, attr->link_create.attach_type);
        link->cgroup = cgrp;

        err = bpf_link_prime(&link->link, &link_primer);
        if (err) {
                kfree(link);
                goto out_put_cgroup;
        }

        err = cgroup_bpf_attach(cgrp, NULL, NULL, link,
                                link->link.attach_type, BPF_F_ALLOW_MULTI | attr->link_create.flags,
                                attr->link_create.cgroup.relative_fd,
                                attr->link_create.cgroup.expected_revision);
        if (err) {
                bpf_link_cleanup(&link_primer);
                goto out_put_cgroup;
        }

        return bpf_link_settle(&link_primer);

out_put_cgroup:
        cgroup_put(cgrp);
        return err;
}

int cgroup_bpf_prog_query(const union bpf_attr *attr,
                          union bpf_attr __user *uattr)
{
        struct cgroup *cgrp;
        int ret;

        cgrp = cgroup_get_from_fd(attr->query.target_fd);
        if (IS_ERR(cgrp))
                return PTR_ERR(cgrp);

        ret = cgroup_bpf_query(cgrp, attr, uattr);

        cgroup_put(cgrp);
        return ret;
}

/**
 * __cgroup_bpf_run_filter_skb() - Run a program for packet filtering
 * @sk: The socket sending or receiving traffic
 * @skb: The skb that is being sent or received
 * @atype: The type of program to be executed
 *
 * If no socket is passed, or the socket is not of type INET or INET6,
 * this function does nothing and returns 0.
 *
 * The program type passed in via @type must be suitable for network
 * filtering. No further check is performed to assert that.
 *
 * For egress packets, this function can return:
 *   NET_XMIT_SUCCESS    (0)    - continue with packet output
 *   NET_XMIT_DROP       (1)    - drop packet and notify TCP to call cwr
 *   NET_XMIT_CN         (2)    - continue with packet output and notify TCP
 *                                to call cwr
 *   -err                       - drop packet
 *
 * For ingress packets, this function will return -EPERM if any
 * attached program was found and if it returned != 1 during execution.
 * Otherwise 0 is returned.
 */
int __cgroup_bpf_run_filter_skb(struct sock *sk,
                                struct sk_buff *skb,
                                enum cgroup_bpf_attach_type atype)
{
        unsigned int offset = -skb_network_offset(skb);
        struct sock *save_sk;
        void *saved_data_end;
        struct cgroup *cgrp;
        int ret;

        if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
                return 0;

        cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        save_sk = skb->sk;
        skb->sk = sk;
        __skb_push(skb, offset);

        /* compute pointers for the bpf prog */
        bpf_compute_and_save_data_end(skb, &saved_data_end);

        if (atype == CGROUP_INET_EGRESS) {
                u32 flags = 0;
                bool cn;

                ret = bpf_prog_run_array_cg(&cgrp->bpf, atype, skb,
                                            __bpf_prog_run_save_cb, 0, &flags);

                /* Return values of CGROUP EGRESS BPF programs are:
                 *   0: drop packet
                 *   1: keep packet
                 *   2: drop packet and cn
                 *   3: keep packet and cn
                 *
                 * The returned value is then converted to one of the NET_XMIT
                 * or an error code that is then interpreted as drop packet
                 * (and no cn):
                 *   0: NET_XMIT_SUCCESS  skb should be transmitted
                 *   1: NET_XMIT_DROP     skb should be dropped and cn
                 *   2: NET_XMIT_CN       skb should be transmitted and cn
                 *   3: -err              skb should be dropped
                 */

                cn = flags & BPF_RET_SET_CN;
                if (ret && !IS_ERR_VALUE((long)ret))
                        ret = -EFAULT;
                if (!ret)
                        ret = (cn ? NET_XMIT_CN : NET_XMIT_SUCCESS);
                else
                        ret = (cn ? NET_XMIT_DROP : ret);
        } else {
                ret = bpf_prog_run_array_cg(&cgrp->bpf, atype,
                                            skb, __bpf_prog_run_save_cb, 0,
                                            NULL);
                if (ret && !IS_ERR_VALUE((long)ret))
                        ret = -EFAULT;
        }
        bpf_restore_data_end(skb, saved_data_end);
        __skb_pull(skb, offset);
        skb->sk = save_sk;

        return ret;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_skb);

/**
 * __cgroup_bpf_run_filter_sk() - Run a program on a sock
 * @sk: sock structure to manipulate
 * @atype: The type of program to be executed
 *
 * socket is passed is expected to be of type INET or INET6.
 *
 * The program type passed in via @type must be suitable for sock
 * filtering. No further check is performed to assert that.
 *
 * This function will return %-EPERM if any if an attached program was found
 * and if it returned != 1 during execution. In all other cases, 0 is returned.
 */
int __cgroup_bpf_run_filter_sk(struct sock *sk,
                               enum cgroup_bpf_attach_type atype)
{
        struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);

        return bpf_prog_run_array_cg(&cgrp->bpf, atype, sk, bpf_prog_run, 0,
                                     NULL);
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);

/**
 * __cgroup_bpf_run_filter_sock_addr() - Run a program on a sock and
 *                                       provided by user sockaddr
 * @sk: sock struct that will use sockaddr
 * @uaddr: sockaddr struct provided by user
 * @uaddrlen: Pointer to the size of the sockaddr struct provided by user. It is
 *            read-only for AF_INET[6] uaddr but can be modified for AF_UNIX
 *            uaddr.
 * @atype: The type of program to be executed
 * @t_ctx: Pointer to attach type specific context
 * @flags: Pointer to u32 which contains higher bits of BPF program
 *         return value (OR'ed together).
 *
 * socket is expected to be of type INET, INET6 or UNIX.
 *
 * This function will return %-EPERM if an attached program is found and
 * returned value != 1 during execution. In all other cases, 0 is returned.
 */
int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
                                      struct sockaddr_unsized *uaddr,
                                      int *uaddrlen,
                                      enum cgroup_bpf_attach_type atype,
                                      void *t_ctx,
                                      u32 *flags)
{
        struct bpf_sock_addr_kern ctx = {
                .sk = sk,
                .uaddr = uaddr,
                .t_ctx = t_ctx,
        };
        struct sockaddr_storage storage;
        struct cgroup *cgrp;
        int ret;

        if (!sk_is_inet(sk) && !sk_is_unix(sk))
                return 0;

        if (!ctx.uaddr) {
                memset(&storage, 0, sizeof(storage));
                ctx.uaddr = (struct sockaddr_unsized *)&storage;
                ctx.uaddrlen = 0;
        } else {
                ctx.uaddrlen = *uaddrlen;
        }

        cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        ret = bpf_prog_run_array_cg(&cgrp->bpf, atype, &ctx, bpf_prog_run,
                                    0, flags);

        if (!ret && uaddr)
                *uaddrlen = ctx.uaddrlen;

        return ret;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_addr);

/**
 * __cgroup_bpf_run_filter_sock_ops() - Run a program on a sock
 * @sk: socket to get cgroup from
 * @sock_ops: bpf_sock_ops_kern struct to pass to program. Contains
 * sk with connection information (IP addresses, etc.) May not contain
 * cgroup info if it is a req sock.
 * @atype: The type of program to be executed
 *
 * socket passed is expected to be of type INET or INET6.
 *
 * The program type passed in via @type must be suitable for sock_ops
 * filtering. No further check is performed to assert that.
 *
 * This function will return %-EPERM if any if an attached program was found
 * and if it returned != 1 during execution. In all other cases, 0 is returned.
 */
int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
                                     struct bpf_sock_ops_kern *sock_ops,
                                     enum cgroup_bpf_attach_type atype)
{
        struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);

        return bpf_prog_run_array_cg(&cgrp->bpf, atype, sock_ops, bpf_prog_run,
                                     0, NULL);
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_ops);

int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
                                      short access, enum cgroup_bpf_attach_type atype)
{
        struct cgroup *cgrp;
        struct bpf_cgroup_dev_ctx ctx = {
                .access_type = (access << 16) | dev_type,
                .major = major,
                .minor = minor,
        };
        int ret;

        rcu_read_lock();
        cgrp = task_dfl_cgroup(current);
        ret = bpf_prog_run_array_cg(&cgrp->bpf, atype, &ctx, bpf_prog_run, 0,
                                    NULL);
        rcu_read_unlock();

        return ret;
}

BPF_CALL_2(bpf_get_local_storage, struct bpf_map *, map, u64, flags)
{
        /* flags argument is not used now,
         * but provides an ability to extend the API.
         * verifier checks that its value is correct.
         */
        enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
        struct bpf_cgroup_storage *storage;
        struct bpf_cg_run_ctx *ctx;
        void *ptr;

        /* get current cgroup storage from BPF run context */
        ctx = container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx);
        storage = ctx->prog_item->cgroup_storage[stype];

        if (stype == BPF_CGROUP_STORAGE_SHARED)
                ptr = &READ_ONCE(storage->buf)->data[0];
        else
                ptr = this_cpu_ptr(storage->percpu_buf);

        return (unsigned long)ptr;
}

const struct bpf_func_proto bpf_get_local_storage_proto = {
        .func           = bpf_get_local_storage,
        .gpl_only       = false,
        .ret_type       = RET_PTR_TO_MAP_VALUE,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_ANYTHING,
};

BPF_CALL_0(bpf_get_retval)
{
        struct bpf_cg_run_ctx *ctx =
                container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx);

        return ctx->retval;
}

const struct bpf_func_proto bpf_get_retval_proto = {
        .func           = bpf_get_retval,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_1(bpf_set_retval, int, retval)
{
        struct bpf_cg_run_ctx *ctx =
                container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx);

        ctx->retval = retval;
        return 0;
}

const struct bpf_func_proto bpf_set_retval_proto = {
        .func           = bpf_set_retval,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_ANYTHING,
};

static const struct bpf_func_proto *
cgroup_dev_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        const struct bpf_func_proto *func_proto;

        func_proto = cgroup_common_func_proto(func_id, prog);
        if (func_proto)
                return func_proto;

        switch (func_id) {
        case BPF_FUNC_perf_event_output:
                return &bpf_event_output_data_proto;
        default:
                return bpf_base_func_proto(func_id, prog);
        }
}

static bool cgroup_dev_is_valid_access(int off, int size,
                                       enum bpf_access_type type,
                                       const struct bpf_prog *prog,
                                       struct bpf_insn_access_aux *info)
{
        const int size_default = sizeof(__u32);

        if (type == BPF_WRITE)
                return false;

        if (off < 0 || off + size > sizeof(struct bpf_cgroup_dev_ctx))
                return false;
        /* The verifier guarantees that size > 0. */
        if (off % size != 0)
                return false;

        switch (off) {
        case bpf_ctx_range(struct bpf_cgroup_dev_ctx, access_type):
                bpf_ctx_record_field_size(info, size_default);
                if (!bpf_ctx_narrow_access_ok(off, size, size_default))
                        return false;
                break;
        default:
                if (size != size_default)
                        return false;
        }

        return true;
}

const struct bpf_prog_ops cg_dev_prog_ops = {
};

const struct bpf_verifier_ops cg_dev_verifier_ops = {
        .get_func_proto         = cgroup_dev_func_proto,
        .is_valid_access        = cgroup_dev_is_valid_access,
};

/**
 * __cgroup_bpf_run_filter_sysctl - Run a program on sysctl
 *
 * @head: sysctl table header
 * @table: sysctl table
 * @write: sysctl is being read (= 0) or written (= 1)
 * @buf: pointer to buffer (in and out)
 * @pcount: value-result argument: value is size of buffer pointed to by @buf,
 *      result is size of @new_buf if program set new value, initial value
 *      otherwise
 * @ppos: value-result argument: value is position at which read from or write
 *      to sysctl is happening, result is new position if program overrode it,
 *      initial value otherwise
 * @atype: type of program to be executed
 *
 * Program is run when sysctl is being accessed, either read or written, and
 * can allow or deny such access.
 *
 * This function will return %-EPERM if an attached program is found and
 * returned value != 1 during execution. In all other cases 0 is returned.
 */
int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
                                   const struct ctl_table *table, int write,
                                   char **buf, size_t *pcount, loff_t *ppos,
                                   enum cgroup_bpf_attach_type atype)
{
        struct bpf_sysctl_kern ctx = {
                .head = head,
                .table = table,
                .write = write,
                .ppos = ppos,
                .cur_val = NULL,
                .cur_len = PAGE_SIZE,
                .new_val = NULL,
                .new_len = 0,
                .new_updated = 0,
        };
        struct cgroup *cgrp;
        loff_t pos = 0;
        int ret;

        ctx.cur_val = kmalloc_track_caller(ctx.cur_len, GFP_KERNEL);
        if (!ctx.cur_val ||
            table->proc_handler(table, 0, ctx.cur_val, &ctx.cur_len, &pos)) {
                /* Let BPF program decide how to proceed. */
                ctx.cur_len = 0;
        }

        if (write && *buf && *pcount) {
                /* BPF program should be able to override new value with a
                 * buffer bigger than provided by user.
                 */
                ctx.new_val = kmalloc_track_caller(PAGE_SIZE, GFP_KERNEL);
                ctx.new_len = min_t(size_t, PAGE_SIZE, *pcount);
                if (ctx.new_val) {
                        memcpy(ctx.new_val, *buf, ctx.new_len);
                } else {
                        /* Let BPF program decide how to proceed. */
                        ctx.new_len = 0;
                }
        }

        rcu_read_lock();
        cgrp = task_dfl_cgroup(current);
        ret = bpf_prog_run_array_cg(&cgrp->bpf, atype, &ctx, bpf_prog_run, 0,
                                    NULL);
        rcu_read_unlock();

        kfree(ctx.cur_val);

        if (ret == 1 && ctx.new_updated) {
                kfree(*buf);
                *buf = ctx.new_val;
                *pcount = ctx.new_len;
        } else {
                kfree(ctx.new_val);
        }

        return ret;
}

#ifdef CONFIG_NET
static int sockopt_alloc_buf(struct bpf_sockopt_kern *ctx, int max_optlen,
                             struct bpf_sockopt_buf *buf)
{
        if (unlikely(max_optlen < 0))
                return -EINVAL;

        if (unlikely(max_optlen > PAGE_SIZE)) {
                /* We don't expose optvals that are greater than PAGE_SIZE
                 * to the BPF program.
                 */
                max_optlen = PAGE_SIZE;
        }

        if (max_optlen <= sizeof(buf->data)) {
                /* When the optval fits into BPF_SOCKOPT_KERN_BUF_SIZE
                 * bytes avoid the cost of kzalloc.
                 */
                ctx->optval = buf->data;
                ctx->optval_end = ctx->optval + max_optlen;
                return max_optlen;
        }

        ctx->optval = kzalloc(max_optlen, GFP_USER);
        if (!ctx->optval)
                return -ENOMEM;

        ctx->optval_end = ctx->optval + max_optlen;

        return max_optlen;
}

static void sockopt_free_buf(struct bpf_sockopt_kern *ctx,
                             struct bpf_sockopt_buf *buf)
{
        if (ctx->optval == buf->data)
                return;
        kfree(ctx->optval);
}

static bool sockopt_buf_allocated(struct bpf_sockopt_kern *ctx,
                                  struct bpf_sockopt_buf *buf)
{
        return ctx->optval != buf->data;
}

int __cgroup_bpf_run_filter_setsockopt(struct sock *sk, int *level,
                                       int *optname, sockptr_t optval,
                                       int *optlen, char **kernel_optval)
{
        struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        struct bpf_sockopt_buf buf = {};
        struct bpf_sockopt_kern ctx = {
                .sk = sk,
                .level = *level,
                .optname = *optname,
        };
        int ret, max_optlen;

        /* Allocate a bit more than the initial user buffer for
         * BPF program. The canonical use case is overriding
         * TCP_CONGESTION(nv) to TCP_CONGESTION(cubic).
         */
        max_optlen = max_t(int, 16, *optlen);
        max_optlen = sockopt_alloc_buf(&ctx, max_optlen, &buf);
        if (max_optlen < 0)
                return max_optlen;

        ctx.optlen = *optlen;

        if (copy_from_sockptr(ctx.optval, optval,
                              min(*optlen, max_optlen))) {
                ret = -EFAULT;
                goto out;
        }

        lock_sock(sk);
        ret = bpf_prog_run_array_cg(&cgrp->bpf, CGROUP_SETSOCKOPT,
                                    &ctx, bpf_prog_run, 0, NULL);
        release_sock(sk);

        if (ret)
                goto out;

        if (ctx.optlen == -1) {
                /* optlen set to -1, bypass kernel */
                ret = 1;
        } else if (ctx.optlen > max_optlen || ctx.optlen < -1) {
                /* optlen is out of bounds */
                if (*optlen > PAGE_SIZE && ctx.optlen >= 0) {
                        pr_info_once("bpf setsockopt: ignoring program buffer with optlen=%d (max_optlen=%d)\n",
                                     ctx.optlen, max_optlen);
                        ret = 0;
                        goto out;
                }
                ret = -EFAULT;
        } else {
                /* optlen within bounds, run kernel handler */
                ret = 0;

                /* export any potential modifications */
                *level = ctx.level;
                *optname = ctx.optname;

                /* optlen == 0 from BPF indicates that we should
                 * use original userspace data.
                 */
                if (ctx.optlen != 0) {
                        *optlen = ctx.optlen;
                        /* We've used bpf_sockopt_kern->buf as an intermediary
                         * storage, but the BPF program indicates that we need
                         * to pass this data to the kernel setsockopt handler.
                         * No way to export on-stack buf, have to allocate a
                         * new buffer.
                         */
                        if (!sockopt_buf_allocated(&ctx, &buf)) {
                                void *p = kmalloc(ctx.optlen, GFP_USER);

                                if (!p) {
                                        ret = -ENOMEM;
                                        goto out;
                                }
                                memcpy(p, ctx.optval, ctx.optlen);
                                *kernel_optval = p;
                        } else {
                                *kernel_optval = ctx.optval;
                        }
                        /* export and don't free sockopt buf */
                        return 0;
                }
        }

out:
        sockopt_free_buf(&ctx, &buf);
        return ret;
}

int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
                                       int optname, sockptr_t optval,
                                       sockptr_t optlen, int max_optlen,
                                       int retval)
{
        struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        struct bpf_sockopt_buf buf = {};
        struct bpf_sockopt_kern ctx = {
                .sk = sk,
                .level = level,
                .optname = optname,
                .current_task = current,
        };
        int orig_optlen;
        int ret;

        orig_optlen = max_optlen;
        ctx.optlen = max_optlen;
        max_optlen = sockopt_alloc_buf(&ctx, max_optlen, &buf);
        if (max_optlen < 0)
                return max_optlen;

        if (!retval) {
                /* If kernel getsockopt finished successfully,
                 * copy whatever was returned to the user back
                 * into our temporary buffer. Set optlen to the
                 * one that kernel returned as well to let
                 * BPF programs inspect the value.
                 */
                if (copy_from_sockptr(&ctx.optlen, optlen,
                                      sizeof(ctx.optlen))) {
                        ret = -EFAULT;
                        goto out;
                }

                if (ctx.optlen < 0) {
                        ret = -EFAULT;
                        goto out;
                }
                orig_optlen = ctx.optlen;

                if (copy_from_sockptr(ctx.optval, optval,
                                      min(ctx.optlen, max_optlen))) {
                        ret = -EFAULT;
                        goto out;
                }
        }

        lock_sock(sk);
        ret = bpf_prog_run_array_cg(&cgrp->bpf, CGROUP_GETSOCKOPT,
                                    &ctx, bpf_prog_run, retval, NULL);
        release_sock(sk);

        if (ret < 0)
                goto out;

        if (!sockptr_is_null(optval) &&
            (ctx.optlen > max_optlen || ctx.optlen < 0)) {
                if (orig_optlen > PAGE_SIZE && ctx.optlen >= 0) {
                        pr_info_once("bpf getsockopt: ignoring program buffer with optlen=%d (max_optlen=%d)\n",
                                     ctx.optlen, max_optlen);
                        ret = retval;
                        goto out;
                }
                ret = -EFAULT;
                goto out;
        }

        if (ctx.optlen != 0) {
                if (!sockptr_is_null(optval) &&
                    copy_to_sockptr(optval, ctx.optval, ctx.optlen)) {
                        ret = -EFAULT;
                        goto out;
                }
                if (copy_to_sockptr(optlen, &ctx.optlen, sizeof(ctx.optlen))) {
                        ret = -EFAULT;
                        goto out;
                }
        }

out:
        sockopt_free_buf(&ctx, &buf);
        return ret;
}

int __cgroup_bpf_run_filter_getsockopt_kern(struct sock *sk, int level,
                                            int optname, void *optval,
                                            int *optlen, int retval)
{
        struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        struct bpf_sockopt_kern ctx = {
                .sk = sk,
                .level = level,
                .optname = optname,
                .optlen = *optlen,
                .optval = optval,
                .optval_end = optval + *optlen,
                .current_task = current,
        };
        int ret;

        /* Note that __cgroup_bpf_run_filter_getsockopt doesn't copy
         * user data back into BPF buffer when reval != 0. This is
         * done as an optimization to avoid extra copy, assuming
         * kernel won't populate the data in case of an error.
         * Here we always pass the data and memset() should
         * be called if that data shouldn't be "exported".
         */

        ret = bpf_prog_run_array_cg(&cgrp->bpf, CGROUP_GETSOCKOPT,
                                    &ctx, bpf_prog_run, retval, NULL);
        if (ret < 0)
                return ret;

        if (ctx.optlen > *optlen)
                return -EFAULT;

        /* BPF programs can shrink the buffer, export the modifications.
         */
        if (ctx.optlen != 0)
                *optlen = ctx.optlen;

        return ret;
}
#endif

static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
                              size_t *lenp)
{
        ssize_t tmp_ret = 0, ret;

        if (dir->header.parent) {
                tmp_ret = sysctl_cpy_dir(dir->header.parent, bufp, lenp);
                if (tmp_ret < 0)
                        return tmp_ret;
        }

        ret = strscpy(*bufp, dir->header.ctl_table[0].procname, *lenp);
        if (ret < 0)
                return ret;
        *bufp += ret;
        *lenp -= ret;
        ret += tmp_ret;

        /* Avoid leading slash. */
        if (!ret)
                return ret;

        tmp_ret = strscpy(*bufp, "/", *lenp);
        if (tmp_ret < 0)
                return tmp_ret;
        *bufp += tmp_ret;
        *lenp -= tmp_ret;

        return ret + tmp_ret;
}

BPF_CALL_4(bpf_sysctl_get_name, struct bpf_sysctl_kern *, ctx, char *, buf,
           size_t, buf_len, u64, flags)
{
        ssize_t tmp_ret = 0, ret;

        if (!buf)
                return -EINVAL;

        if (!(flags & BPF_F_SYSCTL_BASE_NAME)) {
                if (!ctx->head)
                        return -EINVAL;
                tmp_ret = sysctl_cpy_dir(ctx->head->parent, &buf, &buf_len);
                if (tmp_ret < 0)
                        return tmp_ret;
        }

        ret = strscpy(buf, ctx->table->procname, buf_len);

        return ret < 0 ? ret : tmp_ret + ret;
}

static const struct bpf_func_proto bpf_sysctl_get_name_proto = {
        .func           = bpf_sysctl_get_name,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_PTR_TO_MEM | MEM_WRITE,
        .arg3_type      = ARG_CONST_SIZE,
        .arg4_type      = ARG_ANYTHING,
};

static int copy_sysctl_value(char *dst, size_t dst_len, char *src,
                             size_t src_len)
{
        if (!dst)
                return -EINVAL;

        if (!dst_len)
                return -E2BIG;

        if (!src || !src_len) {
                memset(dst, 0, dst_len);
                return -EINVAL;
        }

        memcpy(dst, src, min(dst_len, src_len));

        if (dst_len > src_len) {
                memset(dst + src_len, '\0', dst_len - src_len);
                return src_len;
        }

        dst[dst_len - 1] = '\0';

        return -E2BIG;
}

BPF_CALL_3(bpf_sysctl_get_current_value, struct bpf_sysctl_kern *, ctx,
           char *, buf, size_t, buf_len)
{
        return copy_sysctl_value(buf, buf_len, ctx->cur_val, ctx->cur_len);
}

static const struct bpf_func_proto bpf_sysctl_get_current_value_proto = {
        .func           = bpf_sysctl_get_current_value,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg3_type      = ARG_CONST_SIZE,
};

BPF_CALL_3(bpf_sysctl_get_new_value, struct bpf_sysctl_kern *, ctx, char *, buf,
           size_t, buf_len)
{
        if (!ctx->write) {
                if (buf && buf_len)
                        memset(buf, '\0', buf_len);
                return -EINVAL;
        }
        return copy_sysctl_value(buf, buf_len, ctx->new_val, ctx->new_len);
}

static const struct bpf_func_proto bpf_sysctl_get_new_value_proto = {
        .func           = bpf_sysctl_get_new_value,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg3_type      = ARG_CONST_SIZE,
};

BPF_CALL_3(bpf_sysctl_set_new_value, struct bpf_sysctl_kern *, ctx,
           const char *, buf, size_t, buf_len)
{
        if (!ctx->write || !ctx->new_val || !ctx->new_len || !buf || !buf_len)
                return -EINVAL;

        if (buf_len > PAGE_SIZE - 1)
                return -E2BIG;

        memcpy(ctx->new_val, buf, buf_len);
        ctx->new_len = buf_len;
        ctx->new_updated = 1;

        return 0;
}

static const struct bpf_func_proto bpf_sysctl_set_new_value_proto = {
        .func           = bpf_sysctl_set_new_value,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
        .arg3_type      = ARG_CONST_SIZE,
};

static const struct bpf_func_proto *
sysctl_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        const struct bpf_func_proto *func_proto;

        func_proto = cgroup_common_func_proto(func_id, prog);
        if (func_proto)
                return func_proto;

        switch (func_id) {
        case BPF_FUNC_sysctl_get_name:
                return &bpf_sysctl_get_name_proto;
        case BPF_FUNC_sysctl_get_current_value:
                return &bpf_sysctl_get_current_value_proto;
        case BPF_FUNC_sysctl_get_new_value:
                return &bpf_sysctl_get_new_value_proto;
        case BPF_FUNC_sysctl_set_new_value:
                return &bpf_sysctl_set_new_value_proto;
        case BPF_FUNC_ktime_get_coarse_ns:
                return &bpf_ktime_get_coarse_ns_proto;
        case BPF_FUNC_perf_event_output:
                return &bpf_event_output_data_proto;
        default:
                return bpf_base_func_proto(func_id, prog);
        }
}

static bool sysctl_is_valid_access(int off, int size, enum bpf_access_type type,
                                   const struct bpf_prog *prog,
                                   struct bpf_insn_access_aux *info)
{
        const int size_default = sizeof(__u32);

        if (off < 0 || off + size > sizeof(struct bpf_sysctl) || off % size)
                return false;

        switch (off) {
        case bpf_ctx_range(struct bpf_sysctl, write):
                if (type != BPF_READ)
                        return false;
                bpf_ctx_record_field_size(info, size_default);
                return bpf_ctx_narrow_access_ok(off, size, size_default);
        case bpf_ctx_range(struct bpf_sysctl, file_pos):
                if (type == BPF_READ) {
                        bpf_ctx_record_field_size(info, size_default);
                        return bpf_ctx_narrow_access_ok(off, size, size_default);
                } else {
                        return size == size_default;
                }
        default:
                return false;
        }
}

static u32 sysctl_convert_ctx_access(enum bpf_access_type type,
                                     const struct bpf_insn *si,
                                     struct bpf_insn *insn_buf,
                                     struct bpf_prog *prog, u32 *target_size)
{
        struct bpf_insn *insn = insn_buf;
        u32 read_size;

        switch (si->off) {
        case offsetof(struct bpf_sysctl, write):
                *insn++ = BPF_LDX_MEM(
                        BPF_SIZE(si->code), si->dst_reg, si->src_reg,
                        bpf_target_off(struct bpf_sysctl_kern, write,
                                       sizeof_field(struct bpf_sysctl_kern,
                                                    write),
                                       target_size));
                break;
        case offsetof(struct bpf_sysctl, file_pos):
                /* ppos is a pointer so it should be accessed via indirect
                 * loads and stores. Also for stores additional temporary
                 * register is used since neither src_reg nor dst_reg can be
                 * overridden.
                 */
                if (type == BPF_WRITE) {
                        int treg = BPF_REG_9;

                        if (si->src_reg == treg || si->dst_reg == treg)
                                --treg;
                        if (si->src_reg == treg || si->dst_reg == treg)
                                --treg;
                        *insn++ = BPF_STX_MEM(
                                BPF_DW, si->dst_reg, treg,
                                offsetof(struct bpf_sysctl_kern, tmp_reg));
                        *insn++ = BPF_LDX_MEM(
                                BPF_FIELD_SIZEOF(struct bpf_sysctl_kern, ppos),
                                treg, si->dst_reg,
                                offsetof(struct bpf_sysctl_kern, ppos));
                        *insn++ = BPF_RAW_INSN(
                                BPF_CLASS(si->code) | BPF_MEM | BPF_SIZEOF(u32),
                                treg, si->src_reg,
                                bpf_ctx_narrow_access_offset(
                                        0, sizeof(u32), sizeof(loff_t)),
                                si->imm);
                        *insn++ = BPF_LDX_MEM(
                                BPF_DW, treg, si->dst_reg,
                                offsetof(struct bpf_sysctl_kern, tmp_reg));
                } else {
                        *insn++ = BPF_LDX_MEM(
                                BPF_FIELD_SIZEOF(struct bpf_sysctl_kern, ppos),
                                si->dst_reg, si->src_reg,
                                offsetof(struct bpf_sysctl_kern, ppos));
                        read_size = bpf_size_to_bytes(BPF_SIZE(si->code));
                        *insn++ = BPF_LDX_MEM(
                                BPF_SIZE(si->code), si->dst_reg, si->dst_reg,
                                bpf_ctx_narrow_access_offset(
                                        0, read_size, sizeof(loff_t)));
                }
                *target_size = sizeof(u32);
                break;
        }

        return insn - insn_buf;
}

const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
        .get_func_proto         = sysctl_func_proto,
        .is_valid_access        = sysctl_is_valid_access,
        .convert_ctx_access     = sysctl_convert_ctx_access,
};

const struct bpf_prog_ops cg_sysctl_prog_ops = {
};

#ifdef CONFIG_NET
BPF_CALL_1(bpf_get_netns_cookie_sockopt, struct bpf_sockopt_kern *, ctx)
{
        const struct net *net = ctx ? sock_net(ctx->sk) : &init_net;

        return net->net_cookie;
}

static const struct bpf_func_proto bpf_get_netns_cookie_sockopt_proto = {
        .func           = bpf_get_netns_cookie_sockopt,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX_OR_NULL,
};
#endif

static const struct bpf_func_proto *
cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        const struct bpf_func_proto *func_proto;

        func_proto = cgroup_common_func_proto(func_id, prog);
        if (func_proto)
                return func_proto;

        switch (func_id) {
#ifdef CONFIG_NET
        case BPF_FUNC_get_netns_cookie:
                return &bpf_get_netns_cookie_sockopt_proto;
        case BPF_FUNC_sk_storage_get:
                return &bpf_sk_storage_get_proto;
        case BPF_FUNC_sk_storage_delete:
                return &bpf_sk_storage_delete_proto;
        case BPF_FUNC_setsockopt:
                if (prog->expected_attach_type == BPF_CGROUP_SETSOCKOPT)
                        return &bpf_sk_setsockopt_proto;
                return NULL;
        case BPF_FUNC_getsockopt:
                if (prog->expected_attach_type == BPF_CGROUP_SETSOCKOPT)
                        return &bpf_sk_getsockopt_proto;
                return NULL;
#endif
#ifdef CONFIG_INET
        case BPF_FUNC_tcp_sock:
                return &bpf_tcp_sock_proto;
#endif
        case BPF_FUNC_perf_event_output:
                return &bpf_event_output_data_proto;
        default:
                return bpf_base_func_proto(func_id, prog);
        }
}

static bool cg_sockopt_is_valid_access(int off, int size,
                                       enum bpf_access_type type,
                                       const struct bpf_prog *prog,
                                       struct bpf_insn_access_aux *info)
{
        const int size_default = sizeof(__u32);

        if (off < 0 || off >= sizeof(struct bpf_sockopt))
                return false;

        if (off % size != 0)
                return false;

        if (type == BPF_WRITE) {
                switch (off) {
                case offsetof(struct bpf_sockopt, retval):
                        if (size != size_default)
                                return false;
                        return prog->expected_attach_type ==
                                BPF_CGROUP_GETSOCKOPT;
                case offsetof(struct bpf_sockopt, optname):
                        fallthrough;
                case offsetof(struct bpf_sockopt, level):
                        if (size != size_default)
                                return false;
                        return prog->expected_attach_type ==
                                BPF_CGROUP_SETSOCKOPT;
                case offsetof(struct bpf_sockopt, optlen):
                        return size == size_default;
                default:
                        return false;
                }
        }

        switch (off) {
        case bpf_ctx_range_ptr(struct bpf_sockopt, sk):
                if (size != sizeof(__u64))
                        return false;
                info->reg_type = PTR_TO_SOCKET;
                break;
        case bpf_ctx_range_ptr(struct bpf_sockopt, optval):
                if (size != sizeof(__u64))
                        return false;
                info->reg_type = PTR_TO_PACKET;
                break;
        case bpf_ctx_range_ptr(struct bpf_sockopt, optval_end):
                if (size != sizeof(__u64))
                        return false;
                info->reg_type = PTR_TO_PACKET_END;
                break;
        case bpf_ctx_range(struct bpf_sockopt, retval):
                if (size != size_default)
                        return false;
                return prog->expected_attach_type == BPF_CGROUP_GETSOCKOPT;
        default:
                if (size != size_default)
                        return false;
                break;
        }
        return true;
}

#define CG_SOCKOPT_READ_FIELD(F)                                        \
        BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, F),       \
                    si->dst_reg, si->src_reg,                           \
                    offsetof(struct bpf_sockopt_kern, F))

#define CG_SOCKOPT_WRITE_FIELD(F)                                       \
        BPF_RAW_INSN((BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, F) |    \
                      BPF_MEM | BPF_CLASS(si->code)),                   \
                     si->dst_reg, si->src_reg,                          \
                     offsetof(struct bpf_sockopt_kern, F),              \
                     si->imm)

static u32 cg_sockopt_convert_ctx_access(enum bpf_access_type type,
                                         const struct bpf_insn *si,
                                         struct bpf_insn *insn_buf,
                                         struct bpf_prog *prog,
                                         u32 *target_size)
{
        struct bpf_insn *insn = insn_buf;

        switch (si->off) {
        case offsetof(struct bpf_sockopt, sk):
                *insn++ = CG_SOCKOPT_READ_FIELD(sk);
                break;
        case offsetof(struct bpf_sockopt, level):
                if (type == BPF_WRITE)
                        *insn++ = CG_SOCKOPT_WRITE_FIELD(level);
                else
                        *insn++ = CG_SOCKOPT_READ_FIELD(level);
                break;
        case offsetof(struct bpf_sockopt, optname):
                if (type == BPF_WRITE)
                        *insn++ = CG_SOCKOPT_WRITE_FIELD(optname);
                else
                        *insn++ = CG_SOCKOPT_READ_FIELD(optname);
                break;
        case offsetof(struct bpf_sockopt, optlen):
                if (type == BPF_WRITE)
                        *insn++ = CG_SOCKOPT_WRITE_FIELD(optlen);
                else
                        *insn++ = CG_SOCKOPT_READ_FIELD(optlen);
                break;
        case offsetof(struct bpf_sockopt, retval):
                BUILD_BUG_ON(offsetof(struct bpf_cg_run_ctx, run_ctx) != 0);

                if (type == BPF_WRITE) {
                        int treg = BPF_REG_9;

                        if (si->src_reg == treg || si->dst_reg == treg)
                                --treg;
                        if (si->src_reg == treg || si->dst_reg == treg)
                                --treg;
                        *insn++ = BPF_STX_MEM(BPF_DW, si->dst_reg, treg,
                                              offsetof(struct bpf_sockopt_kern, tmp_reg));
                        *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, current_task),
                                              treg, si->dst_reg,
                                              offsetof(struct bpf_sockopt_kern, current_task));
                        *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct task_struct, bpf_ctx),
                                              treg, treg,
                                              offsetof(struct task_struct, bpf_ctx));
                        *insn++ = BPF_RAW_INSN(BPF_CLASS(si->code) | BPF_MEM |
                                               BPF_FIELD_SIZEOF(struct bpf_cg_run_ctx, retval),
                                               treg, si->src_reg,
                                               offsetof(struct bpf_cg_run_ctx, retval),
                                               si->imm);
                        *insn++ = BPF_LDX_MEM(BPF_DW, treg, si->dst_reg,
                                              offsetof(struct bpf_sockopt_kern, tmp_reg));
                } else {
                        *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, current_task),
                                              si->dst_reg, si->src_reg,
                                              offsetof(struct bpf_sockopt_kern, current_task));
                        *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct task_struct, bpf_ctx),
                                              si->dst_reg, si->dst_reg,
                                              offsetof(struct task_struct, bpf_ctx));
                        *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_cg_run_ctx, retval),
                                              si->dst_reg, si->dst_reg,
                                              offsetof(struct bpf_cg_run_ctx, retval));
                }
                break;
        case offsetof(struct bpf_sockopt, optval):
                *insn++ = CG_SOCKOPT_READ_FIELD(optval);
                break;
        case offsetof(struct bpf_sockopt, optval_end):
                *insn++ = CG_SOCKOPT_READ_FIELD(optval_end);
                break;
        }

        return insn - insn_buf;
}

static int cg_sockopt_get_prologue(struct bpf_insn *insn_buf,
                                   bool direct_write,
                                   const struct bpf_prog *prog)
{
        /* Nothing to do for sockopt argument. The data is kzalloc'ated.
         */
        return 0;
}

const struct bpf_verifier_ops cg_sockopt_verifier_ops = {
        .get_func_proto         = cg_sockopt_func_proto,
        .is_valid_access        = cg_sockopt_is_valid_access,
        .convert_ctx_access     = cg_sockopt_convert_ctx_access,
        .gen_prologue           = cg_sockopt_get_prologue,
};

const struct bpf_prog_ops cg_sockopt_prog_ops = {
};

/* Common helpers for cgroup hooks. */
const struct bpf_func_proto *
cgroup_common_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        switch (func_id) {
        case BPF_FUNC_get_local_storage:
                return &bpf_get_local_storage_proto;
        case BPF_FUNC_get_retval:
                switch (prog->expected_attach_type) {
                case BPF_CGROUP_INET_INGRESS:
                case BPF_CGROUP_INET_EGRESS:
                case BPF_CGROUP_SOCK_OPS:
                case BPF_CGROUP_UDP4_RECVMSG:
                case BPF_CGROUP_UDP6_RECVMSG:
                case BPF_CGROUP_UNIX_RECVMSG:
                case BPF_CGROUP_INET4_GETPEERNAME:
                case BPF_CGROUP_INET6_GETPEERNAME:
                case BPF_CGROUP_UNIX_GETPEERNAME:
                case BPF_CGROUP_INET4_GETSOCKNAME:
                case BPF_CGROUP_INET6_GETSOCKNAME:
                case BPF_CGROUP_UNIX_GETSOCKNAME:
                        return NULL;
                default:
                        return &bpf_get_retval_proto;
                }
        case BPF_FUNC_set_retval:
                switch (prog->expected_attach_type) {
                case BPF_CGROUP_INET_INGRESS:
                case BPF_CGROUP_INET_EGRESS:
                case BPF_CGROUP_SOCK_OPS:
                case BPF_CGROUP_UDP4_RECVMSG:
                case BPF_CGROUP_UDP6_RECVMSG:
                case BPF_CGROUP_UNIX_RECVMSG:
                case BPF_CGROUP_INET4_GETPEERNAME:
                case BPF_CGROUP_INET6_GETPEERNAME:
                case BPF_CGROUP_UNIX_GETPEERNAME:
                case BPF_CGROUP_INET4_GETSOCKNAME:
                case BPF_CGROUP_INET6_GETSOCKNAME:
                case BPF_CGROUP_UNIX_GETSOCKNAME:
                        return NULL;
                default:
                        return &bpf_set_retval_proto;
                }
        default:
                return NULL;
        }
}